Reading system, reading device, and storage medium

ABSTRACT

According to one embodiment, a reading system includes an extractor, a determiner, and a reader. The extractor extracts a candidate image from an input image. The candidate image is of a portion of the input image in which a segment display is imaged. The determiner calculates an angle with respect to a reference line of each of a plurality of straight lines detected from the candidate image, and determines whether or not the candidate image is an image of a segment display based on a distribution indicating a relationship between the angle and a number of the straight lines. The reader reads a numerical value displayed in a segment display from the candidate image determined to be an image of a segment display.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of International ApplicationPCT/JP2018/035362, filed on Sep. 25, 2018. This application also claimspriority to Japanese Patent Application No. 2018-026500, filed on Feb.16, 2018. The entire contents of each are incorporated herein byreference.

FIELD

Embodiments described herein relate generally to a reading system, areading device, and a storage medium.

BACKGROUND

There is a system that reads a numerical value displayed in a segmentdisplay. It is desirable for the system to have high accuracy of readingthe numerical value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a readingsystem according to an embodiment;

FIG. 2 is a flowchart illustrating the operation of the reading systemaccording to the embodiment;

FIGS. 3A to 3H illustrate the processing according to the reading systemaccording to the embodiment;

FIG. 4 is a block diagram illustrating a configuration of a readingsystem according to a first modification of the embodiment;

FIG. 5 is a block diagram illustrating a configuration of a readingsystem according to a second modification of the embodiment;

FIG. 6 is a block diagram illustrating a configuration of a readingsystem according to a third modification of the embodiment; and

FIG. 7 is a block diagram illustrating a hardware configuration forrealizing the reading systems according to the embodiments.

DETAILED DESCRIPTION

According to one embodiment, a reading system includes an extractor, adeterminer, and a reader. The extractor extracts a candidate image froman input image. The candidate image is of a portion of the input imagein which a segment display is imaged. The determiner calculates an anglewith respect to a reference line of each of a plurality of straightlines detected from the candidate image, and determines whether or notthe candidate image is an image of a segment display based on adistribution indicating a relationship between the angle and a number ofthe straight lines. The reader reads a numerical value displayed in asegment display from the candidate image determined to be an image of asegment display.

Various embodiments are described below with reference to theaccompanying drawings.

In the specification and drawings, components similar to those describedpreviously or illustrated in an antecedent drawing are marked with likereference numerals, and a detailed description is omitted asappropriate.

FIG. 1 is a block diagram illustrating a configuration of a readingsystem according to an embodiment.

The reading system according to the embodiment is used to read anumerical value displayed in a segment display from an image includingthe segment display.

In the embodiment, a segment display refers to a display that includessome display information such as a numeral, a character, etc.,configured by the display of multiple segments.

As illustrated in FIG. 1, the reading system 1 according to theembodiment includes an imager 11, an extractor 12, a converter 13, adeterminer 15, a reader 16, and a memory part 18.

The imager 11 acquires a static image by imaging a segment display. Theimager 11 outputs the acquired image to the extractor 12. When a videoimage is imaged by the imager 11, the imager 11 cuts out a static imagefrom the video image and outputs the static image to the extractor 12.An object other than a segment display may be imaged in the image.

The extractor 12 extracts a candidate of the image of the segmentdisplay from the image that is input. Here, the image that is imaged bythe imager 11 and input to the extractor 12 is called the input image.The image that is a portion of the input image and is a candidate of thesegment display is called the candidate image. The candidate image is aportion of the input image in which the extractor 12 determines that thesegment display is imaged. Multiple candidate images may be output fromthe extractor 12.

As one specific example, the extractor 12 includes a processing part 12a, a binarizer 12 b, a contour extractor 12 c, a first selector 12 d, arectangle extractor 12 e, and a second selector 12 f.

For example, the processing part 12 a generates a processed image inwhich the input image is converted into a grayscale. The processing part12 a outputs the processed image to the binarizer 12 b. At this time,for example, the processing part 12 a may output, to the binarizer 12 b,a processed image in which the input image is reduced to a preset size.At this time, the processing part 12 a stores, in the memory part 18,the original-size image that is not reduced.

The binarizer 12 b generates a binary image illustrated using white andblack by binarizing the processed image that is input. For example, thecontour extractor 12 c extracts the contour of a region illustratedusing white in the binary image.

The first selector 12 d calculates the surface area of the regionsurrounded with the contour. When multiple contours are extracted, thesurface area of each region is calculated. The first selector 12 dcompares each calculated surface area to a prescribed threshold andselects only regions of which the surface area is not less than thethreshold. Thereby, regions of which the surface area is too small areexcluded from the candidates.

The rectangle extractor 12 e extracts a rectangle by performing astraight-line approximation of the selected region. For example, therectangle extractor 12 e acquires the coordinates of the vertices of theextracted rectangle.

The second selector 12 f compares the extracted rectangular region to apreset condition and selects a region matching the condition. Thecondition may be, for example, the ratio of the vertical dimension andthe lateral dimension of the rectangle being within a prescribed range,the angles of the vertices being within a prescribed range, all verticesof the rectangle not being in the outer frame vicinity of the image(e.g., within three pixels from the outer frame), etc. The secondselector 12 f outputs the selected rectangle to the converter 13 as afinal candidate image.

The converter 13 performs the following first processing and secondprocessing.

In the first processing, the converter 13 determines whether or not thecandidate image input from the extractor 12 is distorted. When it isdetermined that the candidate image is distorted, the converter 13corrects the distortion so that the candidate image approaches an imagethat is imaged from the front.

In the second processing, the converter 13 determines whether or not thesize of the candidate image matches a preset specified size. When thesize of the candidate image does not match the specified size, theconverter 13 corrects the candidate image so that the size of thecandidate image approaches the specified size.

For example, the converter 13 corrects the distortion and the size byperforming a projective transformation of the candidate image. Theconverter 13 outputs the corrected candidate image to the determiner 15.When it is determined that the candidate image is not distorted and thesize of the candidate image matches the specified size, the converter 13outputs the input candidate image as-is to the determiner 15.

The determiner 15 includes a straight line detector 15 a, an anglecalculator 15 b, a distribution generator 15 c, a first comparer 15 d,an end point group detector 15 e, an evaluator 15 f, and a secondcomparer 15 g.

The straight line detector 15 a detects multiple straight lines includedin the image on which edge detection is performed. For example, in thedetection of the straight lines, the start points and the end points ofthe line segments are detected. The straight line detector 15 a outputsthe detection result to the angle calculator 15 b and stores thedetection result in the memory part 18. The straight line detector 15 adetects line segments not less than a prescribed length with aprescribed angular resolution.

The angle calculator 15 b calculates the angle with respect to areference line for each straight line. For example, the angle calculator15 b uses the image bottom side (a straight line extending horizontally)as the reference line, and calculates the angle between the referenceline and the straight line for each straight line. Based on thecalculation result, the distribution generator 15 c generates adistribution indicating the relationship between the angle and thenumber of straight lines.

The first comparer 15 d compares the generated distribution and a presetfirst condition. For example, the first condition is when the sum of thetotal number of straight lines at a first angle vicinity and the totalnumber of straight lines at the vicinity of a second angle tilted withrespect to the first angle in the generated distribution is not lessthan a preset value.

For example, the first angle is 0 degrees, and the second angle is 80degrees. The “vicinity” includes, for example, a range not less than −10degrees and not more than +10 degrees with the first angle or the secondangle at the center. In such a case, the first comparer 15 d comparesthe sum of the total number of straight lines within a range not lessthan −10 degrees and not more than 10 degrees and the total number ofstraight lines within a range not less than 70 degrees and not more than90 degrees in the distribution to the preset value.

For example, in the image, the angle of a line parallel to the lateraldirection is taken to be 0 degrees, and the angle of a line parallel tothe vertical direction is taken to be 90 degrees. When the segmentdisplay to be read is a seven-segment display, many straight lines atabout 0 degrees and many straight lines at about 80 degrees aredetected. When the segment display to be read is a fourteen-segmentdisplay or a sixteen-segment display, many straight lines at about 0degrees, many straight lines at about 45 degrees, and many straightlines at about 80 degrees are detected.

The first condition is set based on these characteristics. When thedistribution satisfies the first condition, the likelihood of thecandidate image including a segment display is high.

When the distribution satisfies the first condition, the first comparer15 d outputs the determination result to the end point group detector 15e. When the distribution does not satisfy the first condition, thelikelihood of the candidate image not being included in the segmentdisplay is high; therefore, for example, the processing ends.

When the determination result from the first comparer 15 d is input, forexample, the end point group detector 15 e refers to the detectionresult of the straight lines stored in the memory part 18. Then, fromthe detection result of the straight lines, the end point group detector15 e detects end point groups where end points (start points and endpoints) of straight lines are clustered.

For example, the end point group detector 15 e subdivides the candidateimage into multiple areas (a matrix configuration) at a prescribedspacing in the lateral direction and a prescribed spacing in thevertical direction and extracts, as the end point groups, areas in whicha prescribed number or more of end points exist. Multiple end pointgroups may be detected from the candidate image when a segment displayis included in the candidate image. The positions at which these endpoint groups are detected correspond to the positions of the endportions of the segments.

For example, the evaluator 15 f calculates a vector from one end pointgroup toward an end point group adjacent to the one end point group foreach of the end point groups. For example, the vector is obtained bydetermining the movement amount necessary for the one end point group tobe overlaid on the other end point group. The evaluator 15 f calculatesthe ratio of the sizes of the adjacent vectors and the angle between thevectors. The evaluator 15 f outputs these evaluation values to thesecond comparer 15 g.

The second comparer 15 g compares the evaluation value and the secondcondition. The second condition includes, for example, a first rangerelating to the ratio of the sizes recited above and a second rangerelating to the angle recited above. When the ratio of the sizes recitedabove is within the first range and the angle recited above is withinthe second range, the second comparer 15 g determines that the candidateimage is an image of a segment display and outputs the candidate imageto the reader 16.

For example, a general seven-segment display includes segments (verticalsegments) extending in the vertical direction and segments (lateralsegments) extending in the lateral direction when viewed in front-view.Typically, the ratio of the lengths of the vertical segments issubstantially 1. The ratio of the length of a lateral segment to thelength of a vertical segment is 1 or less. The angle between a verticalsegment and a lateral segment is about 80 degrees or about 100 degrees.The angle between the vertical segments is 180 degrees.

The ratio of the sizes of the vectors calculated by the evaluator 15 fcorresponds to the ratio of the lengths of the vertical segments or theratio of the lengths of the vertical segment and the lateral segment.The angle between the vectors calculated by the evaluator 15 fcorresponds to the angle between the vertical segment and the lateralsegment or the angle between the vertical segments. Accordingly, it canbe determined whether or not the candidate image is an image of asegment display by comparing these evaluation values to the preset firstrange and the preset second range.

When multiple ratios of the sizes and multiple angles are calculated bythe evaluator 15 f, for example, the second comparer 15 g compares eachratio of the sizes to the first range and compares each angle to thesecond range.

For example, the second comparer 15 g detects the total number of ratiosof the sizes that are calculated. The second comparer 15 g detects thenumber of ratios of the sizes that are included in the first range.Then, the second comparer 15 g calculates the proportion of the numberof ratios of the sizes included in the first range to the total number.

Similarly, for example, the second comparer 15 g calculates theproportion of the number of angles that are included in the second rangeto the total number of angles that are calculated.

The second comparer 15 g determines that the candidate image is an imageof a segment display when the two calculated proportions each are notless than preset thresholds.

The reader 16 reads the numerical value displayed in the segment displayfrom the candidate image that is input. For example, the reader 16 cutsout the numeral from the candidate image that is input and reads thenumerical value by detecting the lit segments. For example, the reader16 causes a monitor to display the numerical value that is read and/oroutputs the numerical value to a database.

The memory part 18 stores information necessary for the processing ofthe reading system 1 and data generated in the processing. For example,the thresholds and the conditions that are compared when performing thedeterminations, etc., are stored in the memory part 18.

An operation of the reading system 1 according to the embodiment willnow be described with reference to FIG. 2 to FIG. 3H.

FIG. 2 is a flowchart illustrating the operation of the reading systemaccording to the embodiment.

FIGS. 3A to 3H illustrate the processing according to the reading systemaccording to the embodiment.

The imager 11 acquires an image by imaging a segment display (step S11of FIG. 2). The processing part 12 a processes the input image (step S12a). A processed image in which the input image is reduced and grayscaledand an original-size image in which only grayscaling of the input imageis performed are generated thereby. FIG. 3A is an example of theprocessed image. The binarizer 12 b generates a binary image asillustrated in FIG. 3B by binarizing the processed image (step S12 b).The contour extractor 12 c extracts a contour of the binary image (stepS12 c).

The first selector 12 d selects a region surrounded with the contour(step S12 d). For example, the region that is surrounded with a frame Aas illustrated in FIG. 3C is selected thereby. The rectangle extractor12 e extracts a rectangle from the original-size image based on theextraction result of the rectangle in the selected region (step S12 e).The second selector 12 f selects the extracted rectangle (step S12 f)and outputs the extracted rectangle as a candidate image. FIG. 3Dillustrates the rectangle output as the candidate image. As illustratedin FIG. 3E, the converter 13 converts the candidate image to correct thedistortion. For example, the converter 13 corrects the distortion andthe size by performing a projective transformation of the candidateimage (step S13).

As illustrated in FIG. 3F, the straight line detector 15 a detectsmultiple straight lines SL from the candidate image (step S15 a). FIG.3F and subsequent drawings illustrate only a portion of the candidateimage. The angle calculator 15 b calculates the angle of each straightline SL (step S15 b). As illustrated in FIG. 3G, the distributiongenerator 15 c generates the distribution indicating the relationshipbetween an angle θ and a number N of straight lines (step S15 c).

The first comparer 15 d determines whether or not the distributionsatisfies the first condition (step S15 d). For example, the firstcomparer 15 d makes a fold at an angle between the peak at the vicinityof 0 degrees and the peak at the vicinity of 80 degrees to overlay thesepeaks. The distribution illustrated by the broken line in FIG. 3G isgenerated thereby. The first comparer 15 d calculates the total numberof the number N of straight lines within a range not less than −10degrees and not more than 10 degrees in the distribution and comparesthe total number to a preset value.

When the first condition is satisfied (when the total number is not lessthan the value), the end point group detector 15 e detects end pointgroups EG as illustrated in FIG. 3H from the detection result of thestraight lines illustrated in FIG. 3F (step S15 e). The evaluator 15 fcalculates the vectors connecting the adjacent end point groups to eachother and calculates the evaluation values (the angles and the ratio ofthe sizes) (step S15 f).

The second comparer 15 g determines whether or not the evaluation valuessatisfy the second condition (step S15 g). When the evaluation valuessatisfy the second condition, the reader 16 reads the numerical value ofthe segment display from the candidate image (step S16).

The determiner 15 determines whether or not another candidate imageexists for which steps S15 a to S15 g have not yet been performed (stepS17). When another candidate image exists, step S15 a is performed forthat candidate image. When no other candidate image exists, theprocessing ends.

Effects of the embodiment will now be described.

As described above, when reading the segment display, a candidate imageis extracted from the input image as a candidate of a portion in which asegment display is imaged. Conventionally, for example, a correction ofdistortion or the like of the extracted candidate image is performed asappropriate, and the numerical value of the segment display is read fromthe candidate image.

However, for example, there are cases where a displayer that is similarto a segment display is included in the candidate image. In such a case,there is a possibility that an erroneous detection may occur due toreading the numerical value of the other displayer as the numericalvalue of a segment display.

To suppress such an erroneous detection, the reading system 1 accordingto the embodiment determines whether or not the candidate image includesa segment display based on the result of the straight line detection andthe result of the end point group detection for the candidate image. Thelikelihood of the erroneous detection can be reduced by reading only thecandidate images determined to include segment displays.

The determination that is based on the result of the straight linedetection and the result of the end point group detection utilizesgeneral features of the segment display (the length and the angle of thesegment). Therefore, the reading system 1 is applicable to diversesegment displays, and the numerical values of the segment displays canbe read with higher accuracy.

Although the determination is performed by the two comparers of thefirst comparer 15 d and the second comparer 15 g in the exampleillustrated in FIG. 1 to FIG. 3H, the determination may be performed byonly one of the first comparer 15 d or the second comparer 15 g in thereading system 1. In such a case as well, the reading accuracy of thenumerical value of the segment display can be increased because thecandidate images having a low likelihood of including a segment displaycan be excluded before the reading by the reader 16. To further increasethe reading accuracy, it is desirable for both the first comparer 15 dand the second comparer 15 g to be provided.

Although the reading system 1 according to the embodiment includes theimager 11 in the example illustrated in FIG. 1, the reading system 1 maynot include the imager 11. For example, an image that is imaged byanother imaging device may be input to the reading system 1, and thereading system 1 may read the numerical value of the segment displayfrom the input image.

The reading system 1 may not include the converter 13; however, it isdesirable for the converter 13 to be included to increase the accuracyof the reading.

For example, the accuracy of the match ratio can be increased by thedistortion of the candidate image being corrected by the converter 13.Thereby, the candidate image in which the segment display is imaged canbe sorted more accurately.

An example is shown in FIGS. 3A to 3H in which a numerical valuedisplayed in a seven-segment display is read. However, the segmentdisplay that is readable by the reading system 1 according to theembodiment is not limited to a seven-segment display. The segmentdisplay to be read may be a fourteen-segment display or asixteen-segment display.

The processing of the extractor 12 is modifiable as appropriate as longas the candidate image can be extracted. For example, the processingpart 12 a or the binarizer 12 b is unnecessary when the size of theinput image is small, when the input image is pre-binarized, etc. Theprocessing for extracting the candidate image from the input image alsois modifiable as appropriate. Such modifications are described below.

First Modification

FIG. 4 is a block diagram illustrating a configuration of a readingsystem according to a first modification of the embodiment.

In the example of FIG. 1 to FIG. 3H, the frame of the display region ofthe segment display is rectangular. Therefore, the rectangle extractor12 e is provided in the extractor 12 to match the shape of the displayregion.

When the frame of the display region is circular, an ellipse extractor12 g is provided instead of the rectangle extractor 12 e in theextractor 12 as in the reading system 2 illustrated in FIG. 4. Theellipse extractor 12 g extracts an ellipse from the region selected bythe first selector 12 d. At this time, the ellipse extractor 12 gacquires the coordinates of the extracted ellipse. The ellipse extractor12 g extracts the image of an ellipse corresponding to the coordinatesrecited above from the original-size image and outputs the extractedimage to the second selector 12 f.

The second selector 12 f selects an ellipse that matches a presetcondition by comparing the image of the ellipse that is input to thepreset condition. For example, the flattening of the ellipse, thedistribution of the luminance, etc., are used as the condition. Thesecond selector 12 f outputs the image of the selected ellipse as thecandidate image to the converter 13. Thereafter, the processing issimilar to that of the example described in reference to FIG. 1 to FIG.3H. In other words, the converter 13 corrects the distortion of thecandidate image. Then, after the determination by the determiner 15, thenumerical value of the segment display is read by the reader 16.

Second Modification

FIG. 5 is a block diagram illustrating a configuration of a readingsystem according to a second modification of the embodiment.

Compared to the reading system 1, the reading system 3 illustrated inFIG. 5 includes an extractor 21 instead of the extractor 12 and theconverter 13.

In the reading system 3, before reading the numerical value of thesegment display, only segment displays that are objects of the readingare imaged from the front by the imager 11. Here, the images in whichonly the segment display is imaged from the front are called templateimages.

The extractor 21 includes a feature extractor 21 a, a matcher 21 b, aconverter 21 c, and a searcher 21 d.

The feature extractor 21 a extracts a feature of the input image. Thefeature extractor 21 a extracts features of template images by referringto the template images stored in the memory part 18. Or, the features ofthe template images may be pre-extracted by the feature extractor 21 aand stored in the memory part 18. In such a case, the feature extractor21 a refers to the features of the template images stored in the memorypart 18. The feature extractor 21 a outputs the feature of the inputimage and the features of the template images to the matcher 21 b.

The matcher 21 b calculates a correction amount of the input imagenecessary for matching the feature of the input image to the features ofthe template images. For example, the matcher 21 b calculates thecorrection amount necessary to cause the distorted segment display ofthe input image to approach an image that is imaged from the front. Thematcher 21 b outputs the calculated correction amount and the inputimage to the converter 13.

When the features cannot be matched to each other, the likelihood ishigh that a segment display is not included in the input image.Accordingly, in such a case, for example, the processing ends withoutcalculating the correction amount.

The converter 21 c converts the input image based on the correctionamount that is input. Thereby, when the input image is distorted withrespect to the template image, the distortion is corrected.

The searcher 21 d refers to the template images stored in the memorypart 18. Then, the searcher 21 d searches for portions in the inputimage that match the template images. The searcher 21 d outputs thematching portions as candidate images to the determiner 15.

Thereafter, the processing of the determiner 15 and the reader 16 issimilar to that of the reading system 1 illustrated in FIG. 1.

For example, the extraction of the feature by the feature extractor 21 ais performed using KAZE, AKAZE (Accelerated KAZE), SIFT (Scale-invariantfeature transform), etc. For example, the matching by the matcher 21 bis performed using KNN (K Nearest Neighbor), FLANN (Fast Library forApproximate Nearest Neighbors), etc. For example, the searching by thesearcher 21 d is performed using pattern matching based on thesimilarity between the images.

In the reading system 3 according to the modification, conversion of theinput image using the feature and matching using the template images areperformed. Namely, the entire region of the input image is converted;therefore, compared to the reading system 1, this is effective whenmultiple segment displays exist in the same plane.

Third Modification

FIG. 6 is a block diagram illustrating a configuration of a readingsystem according to a third modification of the embodiment.

Compared to the reading system 1, the reading system 4 illustrated inFIG. 6 includes an extractor 31 instead of the extractor 12 and theconverter 13. The extractor 31 includes a trainer 31 a, an inputter 31b, a detector 31 c, and a processor 31 d.

In the reading system 4, the candidate image in which the segmentdisplay is imaged is extracted from the input image by using a neuralnetwork. For example, teacher data is input to the extractor 31beforehand, and the neural network is trained. The teacher dataincludes, for example, distorted images including segment displays, dataof the positions of the segment displays in the images, and thedistortion amounts of the images.

The trainer 31 a trains the neural network so that when image data isinput, neurons respond (fire) for the data of the portions where thesegment display is imaged, and neurons that correspond to the distortionamount of the image respond. The trainer 31 a stores the trained neuralnetwork in the memory part 18. The training by the trainer 31 a recitedabove may be performed by a processing device that performs theprocessing of the determiner 15 and/or the reader 16 or by anotherprocessing device. Favorably, the training recited above is performed bya processing device having faster calculation performance.

Subsequently, an image for reading the numerical value of the segmentdisplay is acquired by the imager 11, and the image is input to theextractor 31. When the image is input, the inputter 31 b refers to thetrained neural network stored in the memory part 18. Then, the inputter31 b inputs the data of the image to the neural network.

The detector 31 c detects the responses of the neurons if the neuronsrespond while the image data is input to the neural network. Then, thedetector 31 c detects the coordinates and the distortion amount of theimage for which the neurons responded, and outputs the coordinates andthe distortion amount to the processor 31 d.

The processor 31 d extracts a candidate image from the input image basedon the coordinates that are input. The processor 31 d corrects thedistortion of the candidate image based on the distortion amount that isinput. The processor 31 d outputs the corrected candidate image to thedeterminer 15.

The sequence of performing the extraction of the candidate image and thecorrection of the distortion can be modified as appropriate. Forexample, in the processor 31 d, the candidate image may be extractedafter the distortion of the input image is corrected.

Thereafter, the processing of the determiner 15 and the reader 16 issimilar to that of the reading system 1 illustrated in FIG. 1.

In the reading system 3 according to the modification, the cut outand/or the correction of the image is performed using a neural network.Therefore, the candidate image can be extracted with higher accuracyeven when it is difficult to extract the contour from the binarizedimage because the contrast ratio of the display region of the segmentdisplay and the outer frame of the display region is not large.Accordingly, compared to the reading system 1, it is possible to readthe numerical value of the segment display in the input image withhigher accuracy.

FIG. 7 is a block diagram illustrating a hardware configuration forrealizing the reading systems according to the embodiments.

For example, the reading systems according to the embodiments include areading device 5 and an imaging device 6 illustrated in FIG. 7. Thereading device 5 is, for example, a computer and includes ROM (Read OnlyMemory) 51, RAM (Random Access Memory) 52, a CPU (Central ProcessingUnit) 53, and a HDD (Hard Disk Drive) 54.

The ROM 51 stores programs controlling the operations of the computer.The ROM 51 stores programs necessary for causing the computer tofunction as the extractor, the converter, the determiner, the reader,the searcher, etc., of the embodiments described above.

The RAM 52 functions as a memory region where the programs stored in theROM 51 are loaded. The CPU 53 reads a control program stored in the ROM51 and controls the operation of the computer according to the controlprogram. The CPU 53 loads various data obtained by the operation of thecomputer into the RAM 52. The HDD 54 functions as the memory part 18 ofthe embodiments described above and stores information necessary forreading, and information obtained in the reading process.

When the reading system 4 that utilizes a neural network is realizedusing the reading device 5, the reading device 5 also may include a GPU(Graphics Processing Unit) and/or a dedicated chip specifically for theprocessing of the neural network. Instead of the HDD 54, the readingdevice 5 may include an eMMC (embedded Multi Media Card), a SSD (SolidState Drive), a SSHD (Solid State Hybrid Drive), etc.

The imaging device 6 images the subject (the segment display) andtransmits the acquired image to the reading device 5. The imaging device6 is, for example, a camera.

An output device 7 outputs the data (the numerical value of the segmentdisplay that is read) output from the reading device 5 so that the usercan recognize the data. The output device 7 is, for example, a monitor,a printer, a speaker, etc.

For example, the reading device 5, the imaging device 6, and the outputdevice 7 are connected to each other by a wired or wireless technique.Or, these devices may be connected to each other via a network. Or, atleast two of the reading device 5, the imaging device 6, or the outputdevice 7 may be embedded in one device. For example, the reading device5 may be embedded in an integral body with an image processor of theimaging device 6, etc.

By using the reading systems and the reading methods according to theembodiments described above, a numerical value that is displayed in asegment display can be read with higher accuracy. Similarly, a numericalvalue that is displayed in a segment display can be read by a computerwith higher accuracy by using a program for causing the computer tooperate as the reading system.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention. The above embodiments can be practiced incombination with each other.

What is claimed is:
 1. A reading system, comprising: an extractorextracting a candidate image from an input image, the candidate imagebeing of a portion of the input image in which a segment display isimaged; a determiner calculating an angle with respect to a referenceline of each of a plurality of straight lines detected from thecandidate image, and determining whether or not the candidate image isan image of a segment display based on a distribution indicating arelationship between the angle and a number of the straight lines; and areader reading a numerical value displayed in a segment display from thecandidate image determined to be an image of a segment display.
 2. Thesystem according to claim 1, wherein the determiner determines that thecandidate image is an image of a segment display when a sum of a numberof the straight lines at a vicinity of a first angle and a number of thestraight lines at a vicinity of a second angle in the distribution isnot less than a preset value, the second angle being tilted with respectto the first angle.
 3. The system according to claim 1, wherein thedeterminer detects end point groups in the candidate image where endpoints are clustered, the determiner calculates vectors connectingadjacent end point groups to each other, and the determiner performs thedetermination based on, in addition to the distribution, at least one ofa ratio of sizes of adjacent vectors or an angle between the adjacentvectors.
 4. The system according to claim 3, wherein the determinerdetermines that the candidate image is an image of a segment displaywhen a first condition and a second condition are satisfied, the firstcondition being when a sum of a number of the straight lines at avicinity of a first angle and a number of the straight lines at avicinity of a second angle in the distribution is not less than a presetvalue, the second angle being tilted with respect to the first angle,the second condition being when the ratio of the sizes is in a firstrange and the angle is in a second range, the first range and the secondrange being preset.
 5. The system according to claim 1, furthercomprising: a converter performing at least first processing ofconverting, when the candidate image is distorted, the candidate imageto approach an image that is imaged from a front, and second processingof correcting a size of the candidate image to approach a specified sizewhen the size of the candidate image is different from the specifiedsize, the specified size being preset, the determiner performing thedetermination by using the converted candidate image.
 6. The systemaccording to claim 1, wherein the extractor extracts a contour from theinput image, the extractor calculates a surface area of a regionsurrounded with the contour, the extractor extracts, based on thecontour, an image having a prescribed shape from the input image whenthe surface area is not less than a threshold, the threshold beingpreset, and the extractor outputs, as the candidate image, the extractedimage satisfying a condition, the condition being preset.
 7. The systemaccording to claim 1, wherein the extractor searches for a portion ofthe input image matching a template image of a segment display to beread, and extracts the matching portion as the candidate image, thetemplate image being prepared beforehand.
 8. The system according toclaim 7, wherein the extractor extracts a feature from the input image,the extractor corrects the input image to cause the extracted feature tomatch a feature of the template image, and the extractor extracts thecandidate image matching the template image from the corrected inputimage.
 9. The system according to claim 1, wherein the extractor inputsdata of the input image to a neural network, the neural network beingpretrained, and the extractor detects, based on an output result of theneural network, the portion of the input image in which the segmentdisplay is imaged, and extracts the portion as the candidate image. 10.The system according to claim 9, wherein the extractor also corrects adistortion of the candidate image based on the output result of theneural network.
 11. The system according to claim 1, further comprising:an imager acquiring the input image by imaging a segment display. 12.The system according to claim 11, wherein the imager images a videoimage and cuts out, from the video image, the input image in which thesegment display is imaged.
 13. A reading system, comprising: anextractor extracting a candidate image from an input image, thecandidate image being of a portion of the input image in which a segmentdisplay is imaged; a determiner, the determiner detecting end pointgroups in the candidate image where end points are clustered, thedeterminer calculating vectors connecting adjacent end point groups toeach other, the determiner determining whether or not the candidateimage is an image of a segment display based on at least one of a ratioof sizes of adjacent vectors or an angle between the adjacent vectors;and a reader reading a numerical value displayed in a segment displayfrom the candidate image determined to be an image of a segment display.14. The system according to claim 13, wherein the determiner determinesthat the candidate image is an image of a segment display when the ratioof the sizes is in a first range and the angle is in a second range, thefirst range and the second range being preset.
 15. The system accordingto claim 13, further comprising: a converter performing at least firstprocessing of converting, when the candidate image is distorted, thecandidate image to approach an image that is imaged from a front, andsecond processing of correcting a size of the candidate image toapproach a specified size when the size of the candidate image isdifferent from the specified size, the specified size being preset, thedeterminer performing the determination by using the converted candidateimage.
 16. The system according to claim 13, wherein the extractorextracts a contour from the input image, the extractor calculates asurface area of a region surrounded with the contour, the extractorextracts, based on the contour, an image having a prescribed shape fromthe input image when the surface area is not less than a threshold, thethreshold being preset, and the extractor outputs, as the candidateimage, the extracted image satisfying a condition, the condition beingpreset.
 17. The system according to claim 13, wherein the extractorsearches for a portion of the input image matching a template image of asegment display to be read, and extracts the matching portion as thecandidate image, the template image being prepared beforehand.
 18. Thesystem according to claim 17, wherein the extractor extracts a featurefrom the input image, the extractor corrects the input image to causethe extracted feature to match a feature of the template image, and theextractor extracts the candidate image matching the template image fromthe corrected input image.
 19. The system according to claim 13, whereinthe extractor inputs data of the input image to a neural network, theneural network being pretrained, and the extractor detects, based on anoutput result of the neural network, the portion of the input image inwhich the segment display is imaged, and extracts the portion as thecandidate image.
 20. The system according to claim 19, wherein theextractor also corrects a distortion of the candidate image based on theoutput result of the neural network.
 21. The system according to claim13, further comprising: an imager acquiring the input image by imaging asegment display.
 22. The system according to claim 21, wherein theimager images a video image and cuts out, from the video image, theinput image in which the segment display is imaged.
 23. A readingdevice, comprising: an imager acquiring an input image by imaging asegment display; an extractor extracting a candidate image from theinput image, the candidate image being of a portion of the input imagein which a segment display is imaged; a determiner calculating an anglewith respect to a reference line of each of a plurality of straightlines detected from the candidate image, and determining whether or notthe candidate image is an image of a segment display based on adistribution indicating a relationship between the angle and a number ofthe straight lines; and a reader reading a character displayed in asegment display from the candidate image determined to be an image of asegment display.
 24. The device according to claim 23, wherein theimager images a video image and cuts out, from the video image, theinput image in which the segment display is imaged.
 25. A storage mediumstoring a program, the program causing a computer to function as: anextractor extracting a candidate image from an input image, thecandidate image being of a portion of the input image in which a segmentdisplay is imaged; a determiner calculating an angle with respect to areference line of each of a plurality of straight lines detected fromthe candidate image, and determining whether or not the candidate imageis an image of a segment display based on a distribution indicating arelationship between the angle and a number of the straight lines; and areader reading a numerical value displayed in a segment display from thecandidate image determined to be an image of a segment display.